Fluorine-containing liquid crystal compound and application thereof
Technical Field
The invention relates to the technical field of liquid crystal compounds, in particular to a novel fluorine-containing liquid crystal compound and application thereof.
Background
In recent years, liquid crystal display devices have been developed more and more rapidly, and various types of liquid crystal display devices have appeared, such as small-sized liquid crystal display devices for vehicles, portable liquid crystal display devices, ultra-thin liquid crystal display devices, and the like. The development in the art is progressing, taking liquid crystal display as an example, which is characterized by light weight, small occupied space, and convenience in movement, as well as notebook-type personal computers, palm computers, mobile phones, and the like.
The liquid crystal material has great research value and good application prospect in the fields of information display materials, organic optoelectronic materials and the like. At present, the TFT-LCD product technology has matured, and successfully solves the technical problems of viewing angle, resolution, color saturation, brightness, etc., and large-size and medium-and small-size TFT-LCD displays have gradually occupied the mainstream status of flat panel displays in respective fields. Meanwhile, the requirements for display technologies are continuously increasing, for example, a liquid crystal display is required to achieve faster response, and a driving voltage is reduced to reduce power consumption, so that a liquid crystal material is required to have low-voltage driving, fast response, a wide temperature range, good low-temperature stability, and other properties.
The liquid crystal material plays an important role in improving the performance of the liquid crystal display, and particularly, the performance of the liquid crystal display can be obviously improved by reducing the rotational viscosity of the liquid crystal material and improving the dielectric anisotropy delta epsilon of the liquid crystal material. Therefore, in order to improve the properties of liquid crystal materials to meet new requirements, the synthesis of liquid crystal compounds with novel structures and the study of the structure-property relationship have become an important work in the liquid crystal field.
Disclosure of Invention
The invention aims to develop a novel fluorine-containing liquid crystal compound, in particular to a fluorobenzofuran-containing liquid crystal compound which has higher negative dielectric anisotropy, good liquid crystal intersolubility, relatively low rotational viscosity and the like, can improve the performance of a liquid crystal material, and has important application value.
In a first aspect, the present invention provides a fluorine-containing liquid crystal compound having a structure represented by general formula (I):
wherein R is1And R2Independently of one another, an alkyl, alkoxy or alkenyl radical having 1 to 12 carbon atoms;
A1、A2and A3Independently of one another, 1, 4-phenylene, 1, 4-cyclohexylene, 1, 4-cyclohexenylene or fluoro-1, 4-phenylene;
Z1、Z2and Z3Independently of each other, represents a single bond, a double bond, an oxygen atom, -CF2O-、-CH2CH2-、-CH2O-、-OCH2-or-CH ═ CH-;
x represents an oxygen atom, a sulfur atom, -CH2-、-CF2-or-CHF-;
m, n, p independently of one another represent 0, 1 or 2.
Wherein the fluoro 1, 4-phenylene is mono-fluoro 1, 4-phenylene, difluoro 1, 4-phenylene, trifluoro 1, 4-phenylene or tetrafluoro 1, 4-phenylene; preferably, the fluoro 1, 4-phenylene is mono-fluoro 1, 4-phenylene or di-fluoro 1, 4-phenylene.
As a preferred embodiment of the present invention, said X represents an oxygen atom.
As a preferred embodiment of the present invention, said m, n, p represent independently of each other 0 or 1.
As a preferred embodiment of the present invention, said R1And R2Independently of one another, an alkyl, alkoxy or alkenyl radical having 1 to 5 carbon atoms.
Further preferably, said R1And R2Independently of one another, represents an alkyl, alkoxy or alkenyl group having 2 to 5 carbon atoms.
More preferably, said R1And R2Independently of one another, from the group consisting of ethyl, n-propyl, n-butyl, n-pentyl, ethoxy.
As a preferred embodiment of the present invention, Z is1、Z2And Z3All represent single bonds.
In a preferred embodiment of the present invention, the fluorine-containing liquid crystal compound is selected from the group consisting of structures represented by any one of the following general formulae I-1 to I-17:
wherein, in the general formulas I-1 to I-17, R is1And R2Each independently of the other represents an alkyl, alkoxy or alkenyl group having 1 to 5 carbon atoms.
More preferably, in the above general formulae I-1 to I-17, R is1And R2Each independently of the other represents an alkyl, alkoxy or alkenyl group having 2 to 5 carbon atoms.
More preferably, in the above general formulae I-1 to I-17, R is1And R2Are each independently of the others selected from ethyl, n-propyl, n-butyl, n-pentyl, ethoxy.
As a preferred embodiment of the present invention, the fluorine-containing liquid crystal compound is any compound selected from the group consisting of compounds represented by the following structures:
in a second aspect, the invention provides a preparation method of the fluorine-containing liquid crystal compound, which can be synthesized by the following methods according to different substituents in the general formula.
In the first method, when m, n and p in the formula (I) are all 0, the fluorine-containing liquid crystal compound has the formula:
the synthetic route is as follows:
the synthesis method comprises the following steps:
(1) to be provided with
And
prepared by Suzuki reaction as raw material
(2) The above-mentioned
Under alkaline conditions, a ring closure reaction is carried out to obtain
Wherein, the
And
the reaction molar ratio of (1) to (0.9-1.2) and the reaction temperature of 60-120 ℃.
The above-mentioned
The molar ratio of the alkali to the alkali is 1: 1-4, and the reaction temperature is 70-150 ℃; wherein the adopted alkali is any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and potassium tert-butoxide, and the preferred alkali is potassium tert-butoxide and/or potassium carbonate.
In the second method, when n is 0 and m and p are not both 0 in the general formula (I), the synthetic route is as follows:
the synthesis method comprises the following steps:
(1) to be provided with
And
prepared by Suzuki reaction as raw material
(2) The above-mentioned
Under alkaline conditions, a ring closure reaction is carried out to obtain
Wherein the content of the first and second substances,
and
the reaction molar ratio of (1) to (0.9-1.2) and the reaction temperature of 60-120 ℃.
Wherein, the
The molar ratio of the alkali to the alkali is 1: 1-4, and the reaction temperature is 70-150 ℃; wherein the adopted alkali is any one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and potassium tert-butoxide, and the preferred alkali is potassium tert-butoxide and/or potassium carbonate.
In the third method, when n is 1, m and p are 0 at the same time, and Z is2Represents a single bond, A2When represents 1, 4-cyclohexylene, the structural formula is:
the synthetic route is as follows:
the synthesis method comprises the following steps:
(1) to be provided with
With an organolithium reagent and then with
Reacting, then dehydrating to obtain
(2) The above-mentioned
Through hydrogenation reaction, obtain
Wherein the content of the first and second substances,
an organic lithium reagent,
The reaction molar ratio of (1) to (1.0-4.0) to (0.8-1.5), and the reaction temperature of-50 to-100 ℃; the organic lithium reagent is selected from any one or more of sec-butyl lithium, tert-butyl lithium and n-butyl lithium; the dehydrating agent used for dehydration is any one or more of p-toluenesulfonic acid, potassium bisulfate and sodium bisulfate.
The hydrogenation reaction in the second step adopts any one or more of palladium carbon, ruthenium carbon and nickel as catalyst, and the dosage of the catalyst is
0.1-10% of mole number.
In the above respective production methods, the R1And R2As defined above.
The liquid crystal compound can be stably and efficiently obtained by the preparation method.
In a third aspect, the invention provides a liquid crystal material composition, which comprises the fluorine-containing liquid crystal compound. The fluorine-containing liquid crystal compound is 0.1-60% by mass, preferably 1-40% by mass, and more preferably 3-25% by mass of the composition.
In a fourth aspect, the invention provides the application of the fluorine-containing liquid crystal compound or the liquid crystal material composition in the liquid phase display field.
As a preferred embodiment, the invention provides the application of the fluorine-containing liquid crystal compound or the liquid crystal material composition in a liquid phase display device.
Preferably, the liquid crystal display device includes, but is not limited to, TN, ADS, VA, PSVA, FFS, IPS, and the like liquid crystal displays.
The invention provides a novel fluorine-containing liquid crystal compound, in particular to a fluorobenzofuran-containing liquid crystal compound which has higher negative dielectric anisotropy, good liquid crystal intersolubility, relatively low rotational viscosity and the like, is required by liquid crystal material improvement and has important application value.
The liquid crystal compound or the composition containing the liquid crystal compound has extremely high negative dielectric anisotropy and low rotational viscosity, so that the driving voltage is effectively reduced, the response speed of a liquid crystal display device is improved, and the liquid crystal compound or the composition containing the liquid crystal compound has the advantages of moderate optical anisotropy value, high charge retention rate and the like, and is a liquid crystal material with excellent performance.
Detailed Description
The technical solution of the present invention will be explained in detail below. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
The starting materials are commercially available from the open literature unless otherwise specified.
Example 1
The liquid crystal compound prepared in this example has the structural formula:
the synthetic route is as follows:
the method comprises the following specific steps:
(1) synthesis of Compound LC-01-1: under the protection of nitrogen, 22g (0.1mol) of 2,3, 4-trifluoro-4-ethoxyphenylboronic acid, 50ml of ethanol, 100ml of toluene, 50ml of water, 13.4g (0.16mol) of sodium bicarbonate and 21.4g (0.1mol) of 2-hydroxy-3-propylbromobenzene are added into a reaction bottle, the temperature is raised to 50 ℃, 0.01g of dichloro-di-tert-butyl- (4-dimethylaminophenyl) phosphine palladium is added, and the temperature is continuously raised to 70 ℃ to 75 ℃ for refluxing for 2 hours. Work-up after the reaction gave 27.9g of a white solid in 90% yield. The white solid obtained, LC-01-1, was analyzed by GC-MS and the product had an M/z of 310 (M)+)。
(2) Synthesis of Compound LC-01: under the protection of nitrogen, 27.9g of compound LC-01-1(0.09mol), 200ml of N-N-dimethylformamide and 20.7g (0.15mol) of potassium carbonate are added into a reaction flask, and the mixture is heated to 110 ℃ to 120 ℃ for reaction for more than 4 hours. Work-up after the reaction gave 24g of a white solid in 92% yield. The white solid obtained, LC-01, was analyzed by GC-MS and the product had an M/z of 290 (M)+)。
Example 2
The liquid crystal compound prepared in this example has the structural formula:
the synthetic route is as follows:
the method comprises the following specific steps:
(1) compound LC-02-1, synthesis: under the protection of nitrogen, 22g (0.1mol) of 2,3, 4-trifluoro-4-ethoxyphenylboronic acid, 60ml of ethanol, 120ml of toluene, 60ml of water, 22g (0.16mol) of potassium carbonate and 29.6g (0.1mol) of trans-3-propylcyclohexyl-2-hydroxy bromobenzene are added into a reaction bottle, the temperature is raised to 50 ℃, 0.01g of dichloro-di-tert-butyl- (4-dimethylaminophenyl) phosphine palladium is added, and the temperature is continuously raised to 70 ℃ to 75 ℃ for refluxing for 2 hours. Work-up after the reaction gave 35.3g of a white solid in 90% yield. The white solid obtained, LC-02-1, was analyzed by GC-MS and the M/z of the product was 392 (M)+)。
(2) Synthesis of Compound LC-02: under the protection of nitrogen, 35.3g of compound LC-02-1(0.09mol), 260ml of N-N-dimethylformamide and 12.3g (0.11mol) of potassium tert-butoxide are added into a reaction flask, and the temperature is raised to 110 ℃ to 120 ℃ for reaction for more than 4 hours. Work-up after the reaction gave 31.8g of a white solid in 95% yield. The white solid obtained, LC-02, was analyzed by GC-MS and the product had an M/z of 372 (M)+)。
Example 3
The liquid crystal compound prepared in this example has the structural formula:
the synthetic route is as follows:
the method comprises the following specific steps:
(1) synthesis of Compound LC-03-1: under the protection of nitrogen, 22g (0.1mol) of 2,3, 4-trifluoro-4-ethoxyphenylboronic acid, 60ml of ethanol, 120ml of toluene, 60ml of water, 22g (0.16mol) of potassium carbonate and 29g (0.1mol) of 4-propylphenyl-2-hydroxy bromobenzene are added into a reaction bottle, the temperature is raised to 50 ℃, 0.01g of dichloro-di-tert-butyl- (4-dimethylaminophenyl) phosphine palladium is added, and the temperature is continuously raised to 70 ℃ to 75 ℃ for refluxing for 2 hours. Work-up after the reaction gave 34.7g of a white solid in 90% yield. The white solid LC-03-1 obtained was analyzed by GC-MS and the product had an M/z of 386 (M)+)。
(2) Synthesis of Compound LC-03: under the protection of nitrogen, 34.7g of compound LC-03-1(0.09mol), 260ml of N-N-dimethylformamide and 12.3g (0.11mol) of potassium tert-butoxide are added into a reaction flask, and the temperature is raised to 110 ℃ to 120 ℃ for reaction for more than 4 hours. Work-up after the reaction gave 31.2g of a white solid in 95% yield. The white solid obtained, LC-03, was analyzed by GC-MS and the product had an M/z of 366 (M)+)。
Example 4
The liquid crystal compound prepared in this example has the structural formula:
the synthetic route is as follows:
the method comprises the following specific steps:
(1) synthesis of Compound LC-04-1: under the protection of nitrogen, adding 23.2(0.10mol) of 2, 3-difluoro-9-ethyl-dibenzofuran and 180ml of tetrahydrofuran into a reaction bottle, controlling the temperature to be-75 to-85 ℃, dropwise adding 0.12mol of n-butyl lithium n-hexane solution, keeping the temperature for 2 hours after dropwise adding, controlling the temperature to be-75 to-85 ℃, dropwise adding 14g of 4-propylcyclohexyl ketone (0.10mol), and naturally returning the temperature to-60 ℃ and keeping the temperature for 2 hours. Adding 200ml of water for quenching reaction, adding 160ml of toluene, washing with water, separating liquid, adding 5g of p-toluenesulfonic acid, refluxing, separating water for 6 hours, and performing conventional aftertreatment to obtain 24.8g of light yellow solid, namely a compound LC-04-1, GC: 99.8% and a yield of 70.0%. The solid LC-04-1 obtained was analyzed by GC-MS and the product had an M/z of 354 (M)+)。
(2) Synthesis of Compound LC-04: under the protection of nitrogen, 24.8g of compound LC-04-1(0.07mol), 160ml of toluene, 40ml of ethanol, 2.5g of 5% palladium carbon and 0.5MPa of hydrogen pressure are added into a hydrogenation kettle, the temperature is raised to 40-60 ℃, and the reaction is carried out for more than 4 hours. Work-up after the reaction gave 15g of a white solid in 60% yield. The white solid obtained LC-04 was subjected to GC-MSAnalysis showed that the M/z of the product was 356 (M)+)。
In the preparation process, the conventional post-treatment is involved if necessary, and the conventional post-treatment specifically comprises the following steps: extracting with dichloromethane, ethyl acetate or toluene, separating, washing with water, drying, evaporating with vacuum rotary evaporator, and purifying the product by vacuum distillation or recrystallization and/or chromatographic separation.
The liquid crystal compounds prepared in examples 1 to 4 of the present invention were subjected to a mixed crystal test as described below. According to the conventional detection method in the field, various performance parameters of the liquid crystal compound are obtained through linear fitting, wherein the specific meanings of the performance parameters are as follows:
n represents the crystalline to nematic melting point (. degree. C.) of the liquid crystal;
CP represents the clearing point of the liquid crystal;
Δ n represents optical anisotropy (25 ℃);
Δ ε represents the dielectric anisotropy (25 ℃, 1000 Hz);
γ 1 represents the rotational viscosity (mPa.s, 25 ℃).
The liquid crystal monomers in the following mixed crystal examples can be synthesized by a known method or commercially available.
Mixed crystal example 1
The liquid crystal compound provided in embodiment 1 of the present invention and other liquid crystal monomers are prepared into a mixed crystal composition, and the mixture ratio and the detection results of the components are shown in table 1 below.
The liquid crystal compound of example 1 in table 1 was replaced with comparative compound 1, of the formula:
in comparison with the compound 1, which is a compound,
thus obtaining a comparative example, and the proportion and the detection result of the components of the comparative example are shown in the table 2.
TABLE 1
TABLE 2
Mixed crystal example 2
The liquid crystal compound provided by embodiment 3 of the present invention and other liquid crystal monomers are prepared into a mixed crystal composition, and the mixture ratio and the detection results of the components are shown in table 3 below.
The liquid crystal compound of example 3 in table 3 was substituted for comparative compound 2, the structural formula is as follows:
the compound of reference 2 was used as a reaction medium,
thus, comparative examples were obtained, and the proportions of the components and the test results of the comparative examples are shown in Table 4.
TABLE 3
TABLE 4
Mixed crystal example 3
The liquid crystal compound provided in embodiment 4 of the present invention and other liquid crystal monomers are prepared into a mixed crystal composition, and the mixture ratio and the detection results of the components are shown in table 5 below.
The liquid crystal compound of example 4 in table 5 was replaced with comparative compound 3, of the following structural formula:
in comparison with the compound 3, which was a,
thus, comparative examples were obtained, and the proportions of the components and the test results of the comparative examples are shown in Table 6.
TABLE 5
TABLE 6
As is apparent from the detection results in tables 1 to 6, when the compound of the present invention is specifically applied to a liquid crystal composition of a conventional system, it is found that the compound can improve the dielectric anisotropy Δ ∈ of the liquid crystal composition, while maintaining a low rotational viscosity γ 1 and a suitable refractive index anisotropy Δ n, and the obtained liquid crystal composition has a significant fast response characteristic and a low voltage driving characteristic.
Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.